DESCRIPTION: Support for the 17th Gordon Research Conference on the Chemistry and Biology of Tetrapyrroles is requested. This biennial interdisciplinary conference has stimulated collaborations between basic biologists, chemists an clinicians interested in tetrapyrroles for more than three decades. In association with proteins, tetrapyrroles serve diverse roles as biological redox catalysts, for harvesting of light energy, for oxygen activation/deliver and as signaling molecules. Free tetrapyrroles are also essential nutrients (e.g. vitamin B12), serve as regulators of gene expression (e.g. hemes), and have been utilized as therapeutic agents (e.g. photodynamic cancer therapy, target delivery or radionuclides). Owing to their photodynamic activity, toxicity and lipophilicity, the accumulation of tetrapyrroles (e.g. porphyrins bilirubin) is associated with numerous pathologies of the skin, liver and brain. For these reasons, this conference represents an important venue for exchange between basic and applied researchers on tetrapyrroles and for refinement of new tools and therapies that are under development by the biomedical industry. Funds requested in this application are targeted to support 10 young investigators who have not previously had the opportunity to attend this conference. Two new sessions have been added that will showcase ne advances from young investigators and highlight recent progress from industry. There will be 21 invited speakers, a plenary lecturer and 8 discussion leaders who have been selected for their scientific excellence, recent innovative work and breadth of the program. The remaining 100 conferees will be chosen to ensure a broad representation of women, ethnicity and young scientists from various disciplines in academic, medical research institutions and industry. Strengths of this ongoing Gordon Conference are its disciplinary diversity; focus on new unpublished work, time for discussion, informal atmosphere, and ban on dissemination of conference proceedings.